MTU stands for maximum Transmission Unit. It refers to largest size in bytes of a data packet transmitted over a network. It is indeed applicable to all networked computers. To adjust your MTU on Windows you need to edit your registry. On Windows XP, you need to edit:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<<interface_name>>
where <<interface_name>> is the GUID of your interface.
The first step is to find your interface. To do this, first, start a command prompt (choose Run on your start menu. When the dialog comes up, enter cmd.exe ). Once the command prompt comes up, type ipconfig and hit enter. In the resulting display, make note of the IP Address.
Now, at that same command prompt, enter regedit.exe. This will bring up the registry editor. Notice that navigating the registry is like navigating your file system.
Navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
You will probably see more than one folder unnder Interfaces. Start looking in those folders until you find one with an IPAddress entry that matches your IP Address.
In this folder, you should see an MTU entry. double click on that entry. That will bring up a dialog to edit the entry. Click on the "Decimal" radio button, then change the Value Data to a smaller value. Click O.K. and close the registry editor.
I'm not sure if the changes take place immediately - you may need to restart your machine.
One more thing: BE VERY CAREFUL EDITING THE REGISTRY - editing the wrong value can render your system inoperable. Before you edit, check and recheck that you're editing the right location.
Also, these instructions apply to Windows XP - Windows 2000 and earlier have these values in a different place.
I hope this is helpful.
Dan